AS1323
1.6µA Quiescent Current, Single Cell, DC-DC
Step-up Converter
www.austriamicrosystems.com/DC-DC_Step-Up/AS1323 Revision 1.07 1 - 14
Datasheet
1 General Description
The AS1323 high-efficiency step-up DC-DC converter was designed
specifically for single-cell, battery-powered devices where lowest
quiescent current and high efficiency are essential.
The compact device is available in three fixed-voltage variations and
is perfect for a wide variety of applications where extremely-low
quiescent currents and very-small form factors are critical.
The devices are available as the standard products shown in Table
1. See also Ordering Information on page 13.
Integrated boot circuitry ensures start-up even with very-high load
currents.
The true output disconnect feature completely disconnects the
output from the battery during shutdown.
The device is available in a TSOT23-5 pin package.
Figure 1. AS1323 - Typical Operating Circuit
2 Key Features
! 1.6µA Quie sc ent Current
! Input Vo ltage Range: 0.75 to 2V
! Up to 100mA Output Current
! Fixed Output Voltages: 2.7, 3.0 and 3.3V
! Shutdown Current: 0.1µA
! Output V o ltage Accuracy: ±3%
! Efficiency: Up to 85%
! No External Diode or FETs Needed
! Output Disconnect in Shutdown
! Guaranteed 0.95V Start-Up Voltage
! TSOT23-5 Package
3 Applications
The devices are ideal for single-cell portable devices including
mobile phones, MP3 players, PDAs, remote controls, personal
medical devices, wireless transmitters
and receivers, and any other battery-operated, porta ble dev ice .
Table 1. Standard Products
Model Fixed Output Voltage Package
AS1323-27 2.7V TSOT23-5
AS1323-30 3.0V TSOT23-5
AS1323-33 3.3V TSOT23-5
AS1323
3
SHDNN
1
VBATT
4
VOUT
5
LX
10µF2
VSS
10µF
10µH
4VOUT3SHDNN
2
VSS
1VBATT 5LX
AS1323
www.austriamicrosystems.com/DC-DC_Step-Up/AS1323 Revision 1.07 2 - 14
AS1323
Datasheet - Pin Assignments
4 Pin Assignments
Figure 2. Pin Assignments (Top Vie w)
4.1 Pin Descriptions
Table 2. Pin Descriptions
Pin Number Pin Name Description
1 VBATT Battery Supply Input and Coil Connection
2 VSS Negative Supply and Ground
3 SHDNN Shutdown Input.
0 = Shutdown mode.
1 = Normal operating mode.
4VOUT
Output. This pin also supplies bootstrap power to the device.
5LX
Inductor Connection. This pin is connected to the internal N-channel MOSFET switch drain and P-
channel synchronous rectifier drain.
4VOUT
3
SHDNN
2VSS
1VBATT 5LX
AS1323
www.austriamicrosystems.com/DC-DC_Step-Up/AS1323 Revision 1.07 3 - 14
AS1323
Datashee t - A b s o l u t e M a x i mu m R a t i n g s
5 Absolute Maximum Ratings
Stresses beyond those listed in Table 3 may cause permanent damage to the device. These are stress ratings only, and functional operation of
the device at these or any other conditions beyond those indicated in Electrical Characteristics on page 4 is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
Table 3. Absolute Maximum Ratings
Parameter Min Max Units Comments
VBATT, SHDNN, LX to VSS -0.3 +5 V
Maximum Current VOUT, LX 1 A
Thermal Resistance ΘJA 207.4 ºC/W on PCB
Electro-Static Discharge 2 kV HBM
Operating Temperature Range -40 +85 ºC
Storage Temperature Range -65 +150 ºC
Junction Temperature +150 ºC
Package Body Temperature +260 ºC
The reflow peak soldering temperature (body
temperature) specified is in accordance with IPC/
JEDEC J-STD-020 “Moisture/Reflow Sensitivity
Classification for Non-Hermetic Solid State Surface
Mount Devices”.
The lead finish for Pb-free leaded packages is matte tin
(100% Sn).
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AS1323
Datasheet - Electrical Characteristics
6 Electrical Characteristics
6.1 DC Electrical Characteristics
TAMB = -40°C to +85°C, VBATT = 1.2V, VOUT = VOUT(NOM), SHDNN = VOUT, RLOAD =
∞
, unless otherwise noted. T ypical values are at TA =
25°C.(unless otherwise specified). Limits are 100% production tested at TAMB = 25ºC. Limits over the operating temperature range are
guaranteed by design.
Note: All limits are guaranteed. The parameters with min and max values are guaranteed with production tests or SQC (Statistical Quality
Control) methods.
Table 4. Electrical Characteristics
Symbol Parameter Condition Min Typ Max Unit
VINMIN Minimum Input Voltage 0.75 V
VIN Operating Input V oltage TAMB = 25ºC 0.95 2 V
VINSU Minimum Start-Up
Input Voltage TAMB = 25ºC,
RLOAD = 100Ω0.75 0.95 V
VOUT Output Voltage
AS1323-27 2.619 2.7 2.781
VAS1323-30 2.91 3.0 3.09
AS1323-33 3.201 3.3 3.399
RLOAD Load depended drop
of VOUT VBATT = 1.5V;
ILOAD = 45mA 30 40 mV
RDS-ON N-Channel On-Resistance 0.5 1.0 Ω
P-Channel On-Resistance 0.75 1.5 Ω
ILIMIT N-Channel Switch
Current Limit Programmed at 400mA 400 mA
tON Switch Maximum On-Time 6 µs
Synchronous Rectifier
Zero-Crossing Current 10 mA
IOP-OUT Operating Current
into VBATT VBATT = 1.5V, VOUT = 3.3V,
TAMB = 25ºC 6 µA
IQ-OUT Quiescent Current to VOUT 1.6 3 µA
IQ-BAT Quiescent Current into VBATT VBATT = 1.5V, TAMB = 25ºC 0.3 1 µA
ISDI-OUT 1
1. VOUT is completely disconnec ted (0 V) during shutdown.
Shutdown Current to VOUT 200 nA
ISDI-BAT Shutdown Current into VBATT VBATT = 1.5V, TAMB = 25ºC 100 nA
VIL SHDNN Voltage Threshold, Low 150 mV
VIH SHDNN Voltage Threshold, High 900 mV
ISDI SHDNN Input Bias Current TAMB = 25ºC, VSDI = VOUT 100 300 nA
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AS1323
Datasheet - Typical Operating Characteristics
7 Typical Operating Characteristics
VOUT= 3.3V; TA = 25
°
C; CIN = COUT = 10µF, L = 10µH, ILOAD = 10mA; VBATT = 1.5V; unless otherwise specified.
Figure 3. Efficiency vs. Output Current; VOUT = 3.3V Figure 4. Efficiency vs. Output Current; VOUT = 3.0V
30
40
50
60
70
80
90
0.1 1 10 100
Output Current (mA)
Efficiency (%) .
VIN = 0.95V
VIN = 1.8V
VIN = 1.5V VIN = 1.2V
30
40
50
60
70
80
90
0.1 1 10 100
Output Current (mA)
Ef f iciency (%) .
VIN = 1.8V
VIN = 1.5V
VIN = 1.2V
VIN = 0.95V
Figure 5. Efficiency vs. Output Current; VOUT = 2.7V Figure 6. Efficiency vs. Input Voltage
30
40
50
60
70
80
90
0.1 1 10 100
Output Current (mA )
Ef f iciency (%) .
VIN = 1.8V
VIN = 1.5V
VIN = 1.2V
VIN = 0.95V
30
40
50
60
70
80
90
0.75 1 1.25 1.5 1.75 2
Input Voltage ( V)
Ef ficiency (%) .
Iload = 80µA
Iload = 800µA
Iload = 11mA
Figure 7. Output Voltage vs. Temperature Figure 8. Output Voltage vs. Output Current
3.28
3.285
3.29
3.295
3.3
3.305
3.31
3.315
3.32
-50 -25 0 25 50 75 100 125
Temperature (° C)
O utput V olt age ( V ) .
No Load
ILOAD = 10mA
ILOAD = 30mA
3
3.05
3.1
3.15
3.2
3.25
3.3
3.35
3.4
0 10203040506070
Output Current (mA)
O utput V olt age ( V ) .
VIN = 1.5V
VIN = 1.2V
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AS1323
Datasheet - Typical Operating Characteristics
Figure 9. Output Voltage vs. Input Voltage Figure 10. Shutdown Current vs. Temperature
3.2
3.22
3.24
3.26
3.28
3.3
3.32
3.34
3.36
3.38
3.4
0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7
Input Vol tage ( V)
O utput V olt age ( V ) .
0.1
1
10
100
1000
-50 -25 0 25 50 75 100 125
Temperature (°C)
I nput Current (nA) .
VIN = 1.5V
VIN = 1.2V
Figure 11. Minimum Input Startup Voltage vs. Temperature Figure 12. Output Voltage vs. Input Voltage; VOUT = 2.7V
0.5
0.6
0.7
0.8
0.9
1
-50-25 0 25 50 75100125
Temperatur e (° C)
I nput Voltage ( V ) .
2.62
2.64
2.66
2.68
2.7
2.72
2.74
2.76
2.78
0.75 1 1.25 1.5 1.75 2
Input V oltage (V)
O utput V olt age ( V ) .
IOUT = 0mA
IOUT = 10mA
IOUT = 30mA
Figure 13. Output Voltage vs. Input Voltage; VOUT = 3.0V Figure 14. Output Voltage vs. Input Voltage; VOUT = 3.3V
2.9
2.92
2.94
2.96
2.98
3
3.02
3.04
3.06
3.08
3.1
0.75 1 1.25 1.5 1.75 2
Input Vol tage ( V)
O utput V olt age ( V ) .
IOUT = 0mA
IOUT = 10mA
IOUT = 30mA
3.2
3.22
3.24
3.26
3.28
3.3
3.32
3.34
3.36
3.38
3.4
0.75 1 1.25 1.5 1.75 2
Input V oltage (V)
O utput V olt age ( V ) .
IOUT = 0mA
IOUT = 10mA
IOUT = 30mA
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AS1323
Datasheet - Typical Operating Characteristics
Figure 15. Output Current vs. Input Voltage Figure 16. SHDNN Threshold vs. Input Voltage
20
30
40
50
60
70
80
90
100
110
0.75 1 1.25 1.5 1.75 2
Input Vol tage ( V)
O utput Cur r ent ( m A ) .
VOUT = 2.7V
VOUT = 3.3V
VOUT = 3.0V
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0.8 1 1.2 1.4 1.6 1.8 2
I n put Voltage (V)
SHDNN Threshold Voltage (V) .
Figure 17. Switching Waveform; VOUT = 2.7V Figure 18. Switching Waveform; VOUT = 3.0V
200µs/Div
ILX VOUT
20mA/DIV 50mV/Div
VLX
2V/Div
200µs/Div
ILX VOUT
20mA/DIV 50mV/Div
VLX
2V/Div
Figure 19. Switching Waveform; VOUT = 3.3V
200µs/Div
ILX VOUT
20mA/DIV 50mV/Div
VLX
2V/Div
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AS1323
Datasheet - Detailed Description
8 Detailed Description
The AS1323 is a compact, high-efficiency, step-up DC-DC converter guaranteed to start up with voltages as low as 0.95V, and operate with an
input voltage down to 0.75V. Consuming only 1.6µA of quiescent current, the device includes an integrated synchronous rectifier that eliminates
the need for an external diode and improves overall efficiency by minimizing losses (see Synchronous Rectification on page 8). The AS1323 also
features an active-low shutdown circuit that supply current to 0.1µA.
Figure 20. Block Diagram
8.1 PFM Control
A forced discontinuous, current-limited, pulse-frequency modulation (PFM) control scheme provides ultra-low quiescent current and high
efficiency over a wide output current-range. Rather than using an integrated oscillator, the inductor current is limited by the 400mA N-channel
current limit or by the 6µs switch maximum on-time. After each device-on cycle, the inductor current must ramp to zero before another cycle can
start. When the error comparator senses that the output has fallen below the regulation threshold, another cycle can begin.
8.2 Synchronous Rectification
The integrated synchronous rectifier eliminates the need for an external Schottky diode, reducing cost and PCB space. During normal operation,
while the inductor discharges, the P-channel MOSFET turns on and shunts the MOSFET body diode. Consequently the rectifier voltage drop is
significantly reduced improving efficiency without the need for external components.
8.3 Low-Voltage Startup Circuit
The AS1323 contains a unique low-voltage startup circuit which ensures start-up even with very high load currents. The minimum start-up
voltage is independent of the load current. This device is powered from pin VBATT, guaranteeing startup at input voltages as low as 0.95V.
8.4 Shutdown
The AS1323 enter shutdown when the SHDNN pin is driven low. During shutdown, the output is completely disconnected from the battery.
Shutdown can be pulled as high as 3.6V, regardless of the voltage at pins VBATT or VOUT. For normal operation, connect SHDN to the input.
AS1323
4
VOUT
3
SHDNN
Ref
5
LX
Control
Logic
Startup
System
Timing
2
VSS
Comparator
Voltage
L1
COUT
Comparator
Discharge
Comparator
Charge
1
VBATT
CIN
0.95 to
1.6V
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AS1323
Datasheet - Application In formation
9 Application Information
Figure 21. Typical Application
9.1 Inductor Selection
The control scheme of the AS1323 allows for a wide range if inductor values. A 10µH inductor should be sufficient for most applications (see
Figure 21).
Smaller inductance values typically offer smaller physical size for a given series resistance, allowing the smallest overall circuit dimensions.
Applications using larger inductance values may startup at lower battery voltages, provide higher efficiency and exhibit less ripple, but they may
reduce the maximum output current. This occurs when the inductance is sufficiently large to prevent the maximum current limit (ILIMIT) from
being reached before the maximum on-time (tON) expires (see Electrical Characteristics on page 4).
For maximum output current, the inductor value should be chosen such that the controller reaches the current-limit before the maximum on-time
is triggered:
tONMAX is 6µs (typ)
ILIMIT is 400mA (typ)
For larger inductor values, the peak inductor current (IPEAK) can be determined by:
The inductor’s incremental saturation current rating should be greater than the peak switching current. However, it is generally advisable to bias
the inductor into saturation by as much as 20%, although this will slightly reduce efficiency.
9.2 Maximum Output Current
The maximum output current (IOUTMAX) is a function of IPEAK, VIN, VOUT, and the overall efficiency (η) as indicated in the formula for
determining IOUTMAX:
AS1323
3
SHDNN
1
VBATT
4
VOUT
5
LX
10µF2
VSS
10µF
10µH
LVBATT tON⋅
ILIMIT
--------------------------------
>(EQ 1
)
IPEAK VBATT tON⋅
L
--------------------------------
=(EQ 2
)
IOUTMAX 1
2
---IPEAK VBATT
VOUT
-----------------
⎝⎠
⎛⎞
η⋅⋅ ⋅=(EQ 3)
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AS1323
Datasheet - Application In formation
9.3 Capacitor Selection
Choose input and output capacitors to supply the input and output peak currents with acceptable voltage ripple. The input filter capacitor
(CIN) reduces peak currents drawn from the battery and improves efficiency. Low equivalent series resistance (ESR) capacitors are
recommended.
Note: Ceramic capacitors have the lowest ESR, but low ESR tantalum or polymer capacitors offer a good balance between cost and perfor-
mance.
Output voltage ripple has two components: variations in the charge stored in the output capacitor with each COIL pulse, and the voltage drop
across the capacitor’s ESR caused by the current into and out of the capacitor:
VRIPPLE = VRIPPLE(C) + VRIPPLE(ESR) (EQ 4)
VRIPPLE(ESR) = IPEAK RESR(COUT) (EQ 5)
Where: IPEAK is the peak inductor current.
For ceramic capacitors, the output voltage ripple is typically dominated by VRIPPLE(C). For example, a 10µF ceramic capacitor and a 10µH
inductor typically provide 75mV of output ripple when stepping up from 1.2V to 3.3V at 50mA. Low input-to-output voltage differences require
higher output capacitor values.
Capacitance and ESR variation of temperature should be considered for best performance in applications with wide operating temperature
ranges.
9.4 PC Board Layout Considerations
The AS1323 has been specially designed to be tolerant to PC board parasitic inductances and resistances. However, to achieve maximum
efficiency a careful PC board layout and component selection is vital.
Note: For the optimal performance, the IC’s VSS and the ground leads of the input and output capacitors must be kept less than 5mm apart
using a ground plane. In addition, keep all connections to COIL as short as possible.
The system robustness guarantees a reliable operation even if those recommendations are not fully applied.
VRIPPLE C() 1
2
---L
VOUT VBATT–()COUT⋅
--------------------------------------------------------------
⎝⎠
⎛⎞
IPEAK2IOUT2
–()⋅⋅≈(EQ 6)
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AS1323
Datasheet - Package Drawings and Markings
10 Package Drawings and Markings
The device is available in an TSOT23-5 package.
Figure 22. TSOT23-5 Package
Notes:
1. Dimensions are in millimeters.
2. Dimension D does not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, and gate burrs shall not exceed
0.15mm per end. Dimension E1 does not include interlead flash or protrusion. Interlead flash or protrusion shall not exceed 0.15mm
per side. Dimensions D and E1 are determined at datum H.
3. The package top can be smaller than the package bottom. Dimensions D and E1 are determined at the outermost extremes of the
plastic body exclusive of mold flash, tie bar burrs, gate burrs, and interlead flash, but include any mismatches between the top of the
package body and the bottom. D and E1 are determined at datum H.
Symbol Min Typ Max Notes Symbol Min Typ Max Notes
A 1.00 L 0.30 0.40 0.50
A1 0.01 0.05 0.10 L1 0.60REF
A2 0.84 0.87 0.90 L2 0.25BSC
b 0.30 0.45 N 5
b1 0.31 0.35 0.39 R 0.10
c 0.12 0.15 0.20 R1 0.10 0.25
c1 0.08 0.13 0.16 θ0º 4º 8º
D 2.90BSC 3,4 θ14º 10º 12º
E 2.80BSC 3,4 Tolerances of Form and Position
E1 1.60BSC 3,4 aaa 0.15
e 0.95BSC bbb 0.25
e1 1.90BSC ccc 0.10
ddd 0.20
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AS1323
Datasheet - Ordering Information
11 Ordering Information
The device is available as the standard products shown in Table 5.
Note: All products are RoHS compliant.
Buy our products or get free samples online at ICdirect: http://www.austriamicrosystems.com/ICdirect
Technical Support is found at http://www.austriamicrosystems.com/Technical-Support
For further information and requests, please contact us mailto:sales@austriamicrosystems.com
or find your local distributor at http://www.austriamicrosystems.com/distributor
Design the AS1323 online at http://www.austriamicrosystems.com/analogbench
analogbench is a powerful design and simulation support tool that operates in on-line and off-line mode to evaluate performance and
generate application-specific bill-of-materials for austriamicrosystems' power management devices.
Table 5. Ordering Information
Ordering Code Marking Output Description Delivery Form Package
AS1323-BTTT-27 ASJN 2.7V 1.6µA Quiescent Current, Single Cell, DC-DC
Step-up Converter Tape and Reel TSOT23-5
AS1323-BTTT-30 ASMP 3.0V 1.6µA Quiescent Current, Single Cell, DC-DC
Step-up Converter Tape and Reel TSOT23-5
AS1323-BTTT-33 ASMQ 3.3V 1.6µA Quiescent Current, Single Cell, DC-DC
Step-up Converter Tape and Reel TSOT23-5
www.austriamicrosystems.com/DC-DC_Step-Up/AS1323 Revision 1.07 14 - 14
AS1323
Datasheet
AS1323
Datasheet
Copyrights
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All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of
the copyright owner.
All products and companies mentioned are trademarks or registered trademarks of their respective companies.
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Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale.
austriamicrosystems AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding
the freedom of the described devices from patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at
any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with austriamicrosystems AG for
current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range,
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specifically not recommended without additional processing by austriamicrosystems AG for each application. For shipments of less than 100
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